Spectrum guy is still here but the problem has, hopefully, been solved. The modem they gave me a year ago was a modem/router - so, my Time Machine/Airport router was getting confused by the modem router - like two cars coming to the same intersection - one has to stop to let the other go - and it was timing out while that was happening. He gave me a brand new modem only - it took a while to get my router to recognize it, but finally it did and I'm on a much faster 5G network now (on my phone, too), so all that's good. He's now looking at the outside wires and is going to replace because they're really old.